The invention relates to an alternating current circuit breaker-contactor, notably connecting capacitor banks, comprising per pole a first and a second pair of mechanical contacts, electrically connected in series:
a remote control electromagnet for opening and closing the first pair of mechanical contacts;
an automatic tripping mechanism on a fault opening the second pair of mechanical contacts;
at least one arcing electrode located in proximity to one of the contacts of the second pair to catch the arc drawn when the contacts of the second pair separate.
In a circuit breaker-contactor of the kind mentioned, the first pair of mechanical contacts performs the function of a contactor to make or break the capacitor bank, whereas the second pair of mechanical contacts performs the function of a protective circuit breaker in the event of short-circuits or overloads occurring. The circuit breaker-contactor can be controlled by a varmetric relay allowing making by capacitor banks. The mechanical contacts, ensuring normal making or breaking, have a high endurance, whereas the contacts of the circuit breaker part resist the action of an arc drawn when opening occurs on a short-circuit. Circuit breaker-contactors of the kind mentioned have the drawback that the mechanical contacts of the contactor part wear, due to current peaks of short duration occurring on closing of a capacitive circuit. These current peaks cause micro-bondings of the contacts and rapid erosion of the latter.